Corrugated MEMS heater structure

ABSTRACT

A thermal actuator comprising a first conductive material encased in a second non-conductive expansive material wherein said first conductive material is constructed in the form of a corrugated heater element so as to increase the rate of thermal transfer to said second non-conductive expansive material.

FIELD OF THE INVENTION

The present invention relates to a micro-electro mechanical system (MEMS) device and, in particular, discloses a corrugated heater structure.

The present invention further relates to micro-electro mechanical systems and in particular to heating or cooling devices.

BACKGROUND OF THE INVENTION

The construction of devices utilising micro-electro mechanical techniques (MEMS) is well known. Often, it is necessary to provide for thermal heating of portions of a MEMS device. Ideally, such heating is provided as efficiently as possible especially where the heating is utilised in devices such as thermal actuators. There is often an additional general need for high speed operation of devices using thermal actuators.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved form of thermal heater for utilisation in actuator devices.

In accordance with a first aspect of the present invention there is provided a method of constructing a heater for heating a micro mechanical structure by means of an electric heater element comprising the step of constructing said heater in a corrugated form so as to improve the rate of thermal transfer to said micro mechanical structure. In accordance with a second aspect of the present invention there is provided a thermal actuator comprising a first conductive material encased in a second non-conductive, expansive material, wherein the first constructive material is constructed in the form of a corrugated heater element so as to increase the rate of thermal transfer to the second non-conductive, expansive material.

The preferred embodiment of the present invention will be described with reference to a thermal actuator utilised in an ink jet printer device. Of course, it will be readily evident that other forms of thermal devices being utilised for both heating and cooling can also be constructed so as to take advantage of the principles of the present invention. The present invention should not necessarily be restricted to the field of ink jet printing.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings which:

FIG. 1 is a schematic cross-sectional view of a single ink jet nozzle constructed in accordance with the preferred embodiment;

FIG. 2 is a schematic cross-sectional view of a single ink jet nozzle constructed in accordance with the preferred embodiment, with the thermal actuator in its activated state;

FIG. 3 is a schematic diagram of the conductive layer utilised in the thermal actuator of the ink jet nozzle constructed in accordance with the preferred embodiment;

FIG. 4 is a close-up perspective view of portion A of FIG. 3;

FIG. 5 is a cross-sectional schematic diagram illustrating the construction of a corrugated conductive layer in accordance with the preferred embodiment of the present invention;

FIG. 6 is a schematic cross-sectional diagram illustrating the development of a resist material through a half-toned mask utilised in the fabrication of a single ink jet nozzle in accordance with the preferred embodiment;

FIG. 7 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with the preferred embodiment;

FIG. 8 is a perspective view of a section of an ink jet print head configuration utilising ink jet nozzles constructed in accordance with the preferred embodiment.

FIG. 9 provides a legend of the materials indicated in FIGS. 10 to 23; and

FIG. 10 to FIG. 23 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, there is provided an ink jet printer having ink ejection nozzles from which ink is ejected with the ink ejection being actuated by means of a thermal actuator which includes a "corrugated" copper heating element encased in a polytetrafluoroethylene (PTFE) layer.

Turning now to FIG. 1, there is illustrated a cross-sectional view of a single inkjet nozzle 10 as constructed in accordance with the present embodiment. The inkjet nozzle 10 includes an ink ejection port 11 for the ejection of ink from a chamber 12 by means of actuation of a thermal paddle actuator 13. The thermal paddle actuator 13 comprises an inner copper heating portion 14 and paddle 15 which are encased in an outer PTFE layer 16. The outer PTFE layer 16 has an extremely high coefficient of thermal expansion (approximately 770×10⁻⁶, or around 380 times that of silicon). The PTFE layer 16 is also highly hydrophobic which results in an air bubble 17 being formed under the actuator 13 due to out-gassing etc. The top PTFE layer is treated so as to make it hydrophilic. The heater 14 is also formed within the lower portion of the actuator 13.

The heater 14 is connected at ends 20,21 (see also FIG. 7) to a lower CMOS drive layer 18 containing drive circuitry (not shown). For the purposes of actuation of actuator 13, a current is passed through the copper heater element 14 which heats the bottom surface of actuator 13. Turning now to FIG. 2, the bottom surface of actuator 13, in contact with air bubble 17 remains heated while any top surface heating is carried away by the exposure of the top surface of actuator 13 to the ink within chamber 12. Hence, the bottom PTFE layer expands more rapidly resulting in a general rapid bending upwards of actuator 13 (as illustrated in FIG. 2) which consequentially causes the ejection of ink from ink ejection port 11. An air inlet channel 28 is formed between two nitride layers 42, 26 such that air is free to flow 29 along channel 28 and through holes, e.g. 25, in accordance with any fluctuating pressure influences. The air flow 29 acts to reduce the vacuum on the back surface of actuator 13 during operation. As a result less energy is required for the movement of the actuator 13.

The actuator 13 can be deactivated by turning off the current to heater element 14. This will result in a return of the actuator 13 to its rest position.

The actuator 13 includes a number of significant features. In FIG. 3 there is illustrated a schematic diagram of the conductive layer of the thermal actuator 13. The conductive layer includes paddle 15, which can be constructed from the same material as heater 14, i.e. copper, and which contains a series of holes e.g. 23. The holes are provided for interconnecting layers of PTFE both above and below panel 15 so as to resist any movement of the PTFE layers past the panel 15 and thereby reducing any opportunities for the delamination of the PTFE and copper layers.

Turning to FIG. 4, there is illustrated a close up view of a portion of the actuator 13 of FIG. 1 illustrating the corrugated nature 22 of the heater element 14 within the PTFE nature of actuator 13 of FIG. 1. The corrugated nature 22 of the heater 14 allows for a more rapid heating of the portions of the bottom layer surrounding the corrugated heater. Any resistive heater which is based upon applying a current to heat an object will result in a rapid, substantially uniform elevation in temperature of the outer surface of the current carrying conductor. The surrounding PTFE volume is therefore heated by means of thermal conduction from the resistive element. This thermal conduction is known to proceed, to a first approximation, at a substantially linear rate with respect to distance from a resistive element. By utilising a corrugated resistive element the bottom surface of actuator 13 is more rapidly heated as, on average, a greater volume of the bottom PTFE surface is closer to a portion of the resistive element. Therefore, the utilisation of a corrugated resistive element results in a more rapid heating of the bottom surface layer and therefore a more rapid actuation of the actuator 13. Further, a corrugated heater also assists in resisting any delamination of the copper and PTFE layer.

Turning now to FIG. 5, the corrugated resistive element can be formed by depositing a resist layer 50 on top of the first PTFE layer 51. The resist layer 50 is exposed utilising a mask 52 having a half-tone pattern delineating the corrugations. After development the resist 50 contains the corrugation pattern. The resist layer 50 and the PTFE layer 51 are then etched utilising an etchant that erodes the resist layer 50 at substantially the same rate as the PTFE layer 51. This transfers the corrugated pattern into the PTFE layer 51. Turning to FIG. 6, on top of the corrugated PTFE layer 51 is deposited the copper heater layer 14 which takes on a corrugated form in accordance with its under layer. The copper heater layer 14 is then etched in a serpentine or concertina form. Subsequently, a further PTFE layer 53 is deposited on top of layer 14 so as to form the top layer of the thermal actuator 13. Finally, the second PTFE layer 52 is planarised to form the top surface of the thermal actuator 13 (FIG. 1).

Returning again now to FIG. 1, it is noted that an ink supply can be supplied through a throughway for channel 38 which can be constructed by means of deep anisotropic silicon trench etching such as that available from STS Limited ("Advanced Silicon Etching Using High Density Plasmas" by J. K. Bhardwaj, H. Ashraf, page 224 of Volume 2639 of the SPIE Proceedings in Micro Machining and Micro Fabrication Process Technology). The ink supply flows from channel 38 through the side grill portions e.g. 40 (see also FIG. 7) into chamber 12. Importantly, the grill portions e.g. 40 which can comprise silicon nitride or similar insulating material acts to remove foreign bodies from the ink flow. The grill 40 also helps to pinch the PTFE actuator 13 to a base CMOS layer 18, the pinching providing an important assistance for the thermal actuator 13 so as to ensure a substantially decreased likelihood of the thermal actuator layer 13 separating from a base CMOS layer 18.

A series of sacrificial etchant holes, e.g. 19, are provided in the top wall 48 of the chamber 12 to allow sacrificial etchant to enter the chamber 12 during fabrication so as to increase the rate of etching. The small size of the holes, e.g. 19, does not affect the operation of the device 10 substantially as the surface tension across holes, e.g. 19, stops ink being ejected from these holes, whereas, the larger size hole 11 allows for the ejection of ink.

Turning now to FIG. 7, there is illustrated an exploded perspective view of a single nozzle 10. The nozzles 10 can be formed in layers starting with a silicon wafer device 41 having a CMOS layer 18 on top thereof as required. The CMOS layer 18 provides the various drive circuitry for driving the copper heater elements 14.

On top of the CMOS layer 18 a nitride layer 42 is deposited, providing primarily protection for lower layers from corrosion or etching. Next a PTFE layer 26 is constructed having the aforementioned holes, e.g. 25, and posts, e.g. 27. The structure of the PTFE layer 26 can be formed by first laying down a sacrificial glass layer (not shown) onto which the PTFE layer 26 is deposited. The PTFE layer 26 includes various features, for example, a lower ridge portion 30 in addition to vias for the subsequent material layers.

In construction of the actuator 13 (FIG. 1), the process of creating a first PTFE layer proceeds by laying down a sacrificial layer on top of layer 26 in which the air bubble underneath actuator 13 (FIG. 1) subsequently forms. On top of this is formed a first PTFE layer utilising the relevant mask. Preferably, the PTFE layer includes vias for the subsequent copper interconnections. Next, a copper layer 43 is deposited on top of the first PTFE layer 42 and a subsequent PTFE layer is deposited on top of the copper layer 43, in each case, utilising the required mask.

The nitride layer 46 can be formed by the utilisation of a sacrificial glass layer which is masked and etched as required to form the side walls and the grill 40. Subsequently, the top nitride layer 48 is deposited again utilising the appropriate mask having considerable holes as required. Subsequently, the various sacrificial layers can be etched away so as to release the structure of the thermal actuator.

In FIG. 8 there is illustrated a section of an ink jet print head configuration 90 utilising ink jet nozzles constructed in accordance with the preferred embodiment, e.g. 91. The configuration 90 can be utilised in a three color process 1600 dpi print-head utilising 3 sets of 2 rows of nozzle chambers, e.g. 92,93, which are interconnected to one ink supply channel, e.g. 94, for each set. The 3 supply channels 94, 95, 96 are interconnected to cyan coloured, magenta coloured and yellow coloured ink reservoirs respectively.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:

1. Using a double sided polished wafer, complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process. Relevant features of the wafer at this step are shown in FIG. 10. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 9 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

2. Deposit 1 micron of low stress nitride. This acts as a barrier to prevent ink diffusion through the silicon dioxide of the chip surface.

3. Deposit 2 microns of sacrificial material (e.g. polyimide).

4. Etch the sacrificial layer using Mask 1. This mask defines the PTFE venting layer support pillars and anchor point. This step is shown in FIG. 11.

5. Deposit 2 microns of PTFE.

6. Etch the PTFE using Mask 2. This mask defines the edges of the PTFE venting layer, and the holes in this layer. This step is shown in FIG. 12.

7. Deposit 3 micron of sacrificial material (e.g. polyimide).

8. Etch the sacrificial layer using Mask 3. This mask defines the actuator anchor point. This step is shown in FIG. 13.

9. Deposit 1 micron of PTFE.

10. Deposit, expose and develop 1 micron of resist using Mask 4. This mask is a gray-scale mask which defines the heater vias as well as the corrugated PTFE surface that the heater is subsequently deposited on.

11. Etch the PTFE and resist at substantially the same rate. The corrugated resist thickness is transferred to the PTFE, and the PTFE is completely etched in the heater via positions. In the corrugated regions, the resultant PTFE thickness nominally varies between 0.25 micron and 0.75 micron, though exact values are not critical. This step is shown in FIG. 14.

12. Deposit and pattern resist using Mask 5. This mask defines the heater.

13. Deposit 0.5 microns of gold (or other heater material with a low Young's modulus) and strip the resist. Steps 12 and 13 form a lift-off process. This step is shown in FIG. 15.

14. Deposit 1.5 microns of PTFE.

15. Etch the PTFE down to the sacrificial layer using Mask 6. This mask defines the actuator paddle and the bond pads. This step is shown in FIG. 16.

16. Wafer probe. All electrical connections are complete at this point, and the chips are not yet separated.

17. Plasma process the PTFE to make the top and side surfaces of the paddle hydrophilic. This allows the nozzle chamber to fill by capillarity.

18. Deposit 10 microns of sacrificial material.

19. Etch the sacrificial material down to nitride using Mask 7. This mask defines the nozzle chamber. This step is shown in FIG. 17.

20. Deposit 3 microns of PECVD glass. This step is shown in FIG. 18.

21. Etch to a depth of 1 micron using Mask 8. This mask defines the nozzle rim. This step is shown in FIG. 19.

22. Etch down to the sacrificial layer using Mask 9. This mask defines the nozzle and the sacrificial etch access holes. This step is shown in FIG. 20.

23. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 10. This mask defines the ink inlets which are etched through the wafer. The wafer is also diced by this etch. This step is shown in FIG. 21.

24. Back-etch the CMOS oxide layers and subsequently deposited nitride layers and sacrificial layer through to PTFE using the back-etched silicon as a mask.

25. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in FIG. 22.

26. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer.

27. Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

28. Hydrophobize the front surface of the print heads.

29. Fill the completed print heads with ink and test them. A filled nozzle is shown in FIG. 23.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

The presently disclosed ink jet printing technology is potentially suited to a wide range of printing systems including: colour and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers, high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable colour and monochrome printers, colour and monochrome copiers, colour and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic `minilabs`, video printers, PhotoCD printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.

Further, the present invention can be utilized in many different MEMS devices and ink jet arrangments which utilize a thermal actuator. A number of devices are set out hereinafter.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal inkjet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal inkjet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric inkjet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per print head, but is a major impediment to the fabrication of pagewide print heads with 19,200 nozzles.

Ideally, the inkjet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new inkjet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the inkjet systems described below with differing levels of difficulty. 45 different inkjet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table below.

The inkjet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems.

For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mm long, with a width which depends upon the inkjet type. The smallest print head designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The print head is connected to the camera circuitry by tape automated bonding.

Cross-Referenced Applications

The following table is a guide to cross-referenced patent applications filed concurrently herewith and discussed hereinafter with the reference being utilized in subsequent tables when referring to a particular case:

    ______________________________________                                         Docket                                                                               Refer-                                                                     No. ence Title                                                               ______________________________________                                         IJ01US                                                                               IJ01    Radiant Plunger Ink Jet Printer                                    IJ02US IJ02 Electrostatic Ink Jet Printer                                      IJ03US IJ03 Planar Thermoelastic Bend Actuator Ink Jet                         IJ04US IJ04 Stacked Electrostatic Ink Jet Printer                              IJ05US IJ05 Reverse Spring Lever Ink Jet Printer                               IJ06US IJ06 Paddle Type Ink Jet Printer                                        IJ07US IJ07 Permanent Magnet Electromagnetic Ink Jet Printer                   IJ08US IJ08 Planar Swing Grill Electromagnetic Ink Jet Printer                 IJ09US IJ09 Pump Action Refill Ink Jet Printer                                 IJ10US IJ10 Pulsed Magnetic Field Ink Jet Printer                              IJ11US IJ11 Two Plate Reverse Firing Electromagnetic Ink Jet                     Printer                                                                      IJ12US IJ12 Linear Stepper Actuator Ink Jet Printer                            IJ13US IJ13 Gear Driven Shutter Ink Jet Printer                                IJ14US IJ14 Tapered Magnetic Pole Electromagnetic Ink Jet Printer                           IJ15US IJ15 Linear Spring Electromagnetic Grill Ink Jet                       Printer                                                            IJ16US IJ16 Lorenz Diaphragm Electromagnetic Ink Jet Printer                   IJ17US IJ17 PTFE Surface Shooting Shuttered Oscillating Pressure                              Ink Jet                                                           Printer                                                                      IJ18US IJ18 Buckle Grip Oscillating Pressure Ink Jet Printer                   IJ19US IJ19 Shutter Based Ink Jet Printer                                      IJ20US IJ20 Curling Calyx Thermoelastic Ink Jet Printer                        IJ21US IJ21 Thermal Actuated Ink Jet Printer                                   IJ22US IJ22 Iris Motion Ink Jet Printer                                        IJ23US IJ23 Direct Firing Thermal Bend Actuator Ink Jet Printer                             IJ24US IJ24 Conductive PTFE Ben Activator Vented Ink Jet                      Printer                                                            IJ25US IJ25 Magnetostrictive Ink Jet Printer                                   IJ26US IJ26 Shape Memory Alloy Ink Jet Printer                                 IJ27US IJ27 Buckle Plate Ink Jet Printer                                       IJ28US IJ28 Thermal Elastic Rotary Impeller Ink Jet Printer                    IJ29US IJ29 Thermoelastic Bend Actuator Ink Jet Printer                        IJ30US IJ30 Thermoelastic Bend Actuator Using PTFE and                           Corrugated Copper Ink Jet Printer                                            IJ31US IJ31 Bend Actuator Direct Ink Supply Ink Jet Printer                    IJ32US IJ32 A High Young's Modulus Thermoelastic Ink Jet                         Printer                                                                      IJ33US IJ33 Thermally actuated slotted chamber wall ink jet printer                         IJ34US IJ34 Ink Jet Printer having a thermal actuator                         comprising an                                                        external coiled spring                                                       IJ35US IJ35 Trough Container Ink Jet Printer                                   IJ36US IJ36 Dual Chamber Single Vertical Actuator Ink Jet                      IJ37US IJ37 Dual Nozzle Single Horizontal Fulcrum Actuator Ink                   Jet                                                                          IJ38US IJ38 Dual Nozzle Single Horizontal Actuator Ink Jet                     IJ39US IJ39 A single bend actuator cupped paddle inkjet printing                              device                                                          IJ40US IJ40 A thermally actuated ink jet printer having a series                              of thermal actuator units                                       IJ41US IJ41 A thermally actuated ink jet printer including a tapered                          heater element                                                  IJ42US IJ42 Radial Back-Curling Thermoelastic Ink Jet                          IJ43US IJ43 Inverted Radial Back-Curling Thermoelastic Ink Jet                 IJ44US IJ44 Surface bend actuator vented ink supply inkjet printer                          IJ45US IJ45 Coil Acutuated Magnetic Plate Ink Jet Printer       ______________________________________                                    

Tables of Drop-on-Demand Inkjets

Eleven important characteristics of the fundamental operation of individual inkjet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of inkjet nozzle. While not all of the possible combinations result in a viable inkjet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain inkjet types have been investigated in detail. These are designated IJ01 to IJ45 above.

Other inkjet configurations can readily be derived from these 45 examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into inkjet print heads with characteristics superior to any currently available inkjet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a printer may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

       - ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS)        Actuator        Mechanism Description Advantages Disadvantages Examples        Thermal An electrothermal heater heats the ♦Large force      generated ♦High power ♦Canon Bubblejet             bubble ink to above boiling point, ♦Simple construct       ion ♦Ink carrier limited to water 1979 Endo et al GB             transferring significant heat to the ♦No moving      parts ♦Low efficiency patent 2,007,162         aqueous ink. A bubble nucleates and ♦Fast operation      ♦High temperatures required ♦Xerox heater-in-       pit         quickly forms, expelling the ink. ♦Small chip area      required for ♦High mechanical stress 1990 Hawkins et al           The efficiency of the process is low, actuator ♦Unusua       l materials required USP 4,899,181         with typically less than 0.05% of the  ♦Large drive      transistors ♦Hewlett-Packard TIJ         electrical energy being transformed  ♦Cavitation causes        actuator failure 1982 Vaught et al         into kinetic energy of the drop.  ♦Kogation reduces      bubble formation USP 4,490,728           ♦Large print heads are difficult to           fabricate        Piezoelectric A piezoelectric crystal such as lead ♦Low      power consumption ♦Very large area required for actuator      ♦Kyser et al USP         lanthanum zirconate (PZT) is ♦Many ink types can be      used ♦Difficult to integrate with electronics 3,946,398           electrically activated, and either ♦Fast operation      ♦High voltage drive transistors required ♦Zol       tan USP         expands, shears, or bends to apply ♦High efficiency      ♦Full pagewidth print heads impractical 3,683,212         pressure to the ink, ejecting drops.  due to actuator size .diamond-so       lid.1973 Stemme USP           ♦Requires electrical poling in high field 3,747,120            strengths during manufacture ♦Epson Stylus            ♦Tektronix            ♦IJ04        Electro- An electric field is used to activate ♦Low      power consumption ♦Low maximum strain (approx. 0.01%)      ♦Seiko Epson, Usui et        strictive electrostriction in relaxor materials ♦Many      ink types can be used ♦Large area required for actuator      due to all JP 253401/96         such as lead lanthanum zirconate ♦Low thermal expansion        low strain ♦IJ04         titanate (PLZT) or lead magnesium ♦Electric field      strength ♦Response speed is marginal (˜10 μs)            niobate (PMN). required (approx. 3.5 V/μm) ♦High      voltage drive transistors required          can be generated without ♦Full pagewidth print heads      impractical          difficulty due to actuator size          ♦Does not require electrical          poling        Ferroelectric An electric field is used to induce a ♦Low        power consumption ♦Difficult to integrate with electronic       s ♦IJ04         phase transition between the ♦Many ink types can be      used ♦Unusual materials such as PLZSnT are         antiferroelectric (AFE) and ♦Fast operation (<1 μs)      required         ferroelectric (FE) phase. Perovskite ♦Relatively high      longitudinal ♦Actuators require a large area         materials such as tin modified lead strain         lanthanum zirconate titanate ♦High efficiency         (PLZSnT) exhibit large strains of up ♦Electric field      strength of         to 1% associated with the AFE to FE around 3 V/μm can be         phase transition. readily provided        Electrostatic Conductive plates are separated by a ♦Low      power consumption ♦Difficult to operate electrostatic      ♦IJ02, IJ04        plates compressible or fluid dielectric ♦Many ink types      can be used devices in an aqueous environment         (usually air). Upon application of a ♦Fast operation      ♦The electrostatic actuator will normally         voltage, the plates attract each other  need to be separated from the        ink         and displace ink, causing drop  ♦Very large area      required to achieve         ejection. The conductive plates may  high forces         be in a comb or honeycomb  ♦High voltage drive transisto       rs may be         structure, or stacked to increase the  required         surface area and therefore the force.  ♦Full pagewidth      print heads are not           competitive due to actuator size        Electrostatic A strong electric field is applied to ♦Low        current consumption ♦High voltage required .diamond-solid       .1989 Saito et al, USP        pull on ink the ink, whereupon electrostatic ♦Low      temperature ♦May be damaged by sparks due to air 4,799,068         attraction accelerates the ink towards  breakdown ♦1989        Miura et al,         the print medium.  ♦Required field strength increases      as the USP 4,810,954           drop size decreases ♦Tone-jet           ♦High voltage drive transistors required           ♦Electrostatic field attracts dust        Permanent An electromagnet directly attracts a ♦Low      power consumption ♦Complex fabrication ♦IJ07,        IJ10        magnet permanent magnet, displacing ink ♦Many ink types      can be used ♦Permanent magnetic material such as        electro- and causing drop ejection. Rare earth ♦Fast      operation Neodymium Iron Boron (NdFeB)        magnetic magnets with a field strength around ♦High      efficiency required.         1 Tesla can be used. Examples are: ♦Easy extension from        single ♦High local currents required         Samarium Cobalt (SaCo) and nozzles to pagewidth print ♦C       opper metalization should be used for         magnetic materials in the neodymium heads long electromigration      lifetime and low         iron boron family (NdFeB,  resistivity         NdDyFeBNb, NdDyFeB, etc)  ♦Pigmented inks are usually      infeasible           ♦Operating temperature limited to the           Curie temperature (around 540K)        Soft magnetic A solenoid induced a magnetic field ♦Low      power consumption ♦Complex fabrication ♦IJ01,        IJ05, IJ08, IJ10        core electro- in a soft magnetic core or yoke ♦Many ink      types can be used ♦Materials not usually present in a      ♦IJ12, IJ14, IJ15, IJ17        magnetic fabricated from a ferrous material ♦Fast      operation CMOS fab such as NiFe, CoNiFe, or         such as electroplated iron alloys such ♦High efficiency        CoFe are required         as CoNiFe [I], CoFe, or NiFe alloys. ♦Easy extension      from single ♦High local currents required         Typically, the soft magnetic material nozzles to pagewidth print      ♦Copper metalization should be used for         is in two parts, which are normally heads long electromigration      lifetime and low         held apart by a spring. When the  resistivity         solenoid is actuated, the two parts  ♦Electroplating is        required         attract, displacing the ink.  ♦High saturation flux      density is required           (2.0-2.1 T is achievable with CoNiFe           [1])        Magnetic The Lorenz force acting on a current ♦Low power        consumption ♦Force acts as a twisting motion .diamond-sol       id.IJ06, IJ11, IJ13, IJ16        Lorenz force carrying wire in a magnetic field is ♦Many      ink types can be used ♦Typically, only a quarter of the           utilized. ♦Fast operation solenoid length provides      force in a         This allows the magnetic field to be ♦High efficiency      useful direction         supplied externally to the print head, ♦Easy extension      from single ♦High local currents required         for example with rare earth nozzles to pagewidth print ♦       Copper metalization should be used for         permanent magnets. heads long electromigration lifetime and low              Only the current carrying wire need  resistivity         be fabricated on the print-head,  ♦Pigmented inks are      usually infeasible         simplifying materials requirements.        Magneto- The actuator uses the giant ♦Many ink types can        be used ♦Force acts as a twisting motion ♦F       ischenbeck, USP        striction magnetostrictive effect of materials ♦Fast      operation ♦Unusual materials such as Terfenol-D 4,032,929         such as Terfenol-D (an alloy of ♦Easy extension from      single are required ♦IJ25         terbium, dysprosium and iron nozzles to pagewidth print .diamond-solid       .High local currents required         developed at the Naval Ordnance heads ♦Copper metalizati       on should be used for         Laboratory, hence Ter-Fe-NOL). For ♦High force is      available long electromigration lifetime and low         best efficiency, the actuator should  resistivity         be pre-stressed to approx. 8 MPa.  ♦Pre-stressing may      be required        Surface Ink under positive pressure is held in ♦Low      power consumption ♦Requires supplementary force to effect      ♦Silverbrook, EP 0771        tension a nozzle by surface tension. The ♦Simple      construction drop separation 658 A2 and related        reduction surface tension of the ink is reduced ♦No      unusual materials ♦Requires special ink surfactants patent        applications         below the bubble threshold, causing required in fabrication .diamond-s       olid.Speed may be limited by surfactant         the ink to egress from the nozzle. ♦High efficiency      properties          ♦Easy extension from single          nozzles to pagewidth print          heads        Viscosity The ink viscosity is locally reduced ♦Simple      construction ♦Requires supplementary force to effect      ♦Silverbrook, EP 0771        reduction to select which drops are to be ♦No unusual      materials drop separation 658 A2 and related         ejected. A viscosity reduction can be required in fabrication      ♦Requires special ink viscosity patent applications               achieved electrothermally with most ♦Easy      extension from single properties         inks, but special inks can be nozzles to pagewidth print .diamond-soli       d.High speed is difficult to achieve         engineered for a 100:1 viscosity heads ♦Requires      oscillating ink pressure         reduction.  ♦A high temperature difference           (typically 80 degrees) is required        Acoustic An acoustic wave is generated and ♦Can operate      without a ♦Complex drive circuitry ♦1993      Hadimioglu et         focussed upon the drop ejection nozzle plate ♦Complex      fabrication al, EUP 550,192         region.  ♦Low efficiency ♦1993 Elrod et      al, EUP           ♦Poor control of drop position 572,220           ♦Poor control of drop volume        Thermoelastic An actuator which relies upon ♦Low power      consumption ♦Efficient aqueous operation requires a      ♦IJ03, IJ09, IJ17, IJ18        bend actuator differential thermal expansion upon ♦Many      ink types can be used thermal insulator on the hot side ♦IJ       19, IJ20, IJ21, IJ22         Joule heating is used. ♦Simple planar fabrication      ♦Corrosion prevention can be difficult ♦IJ23,        IJ24, IJ27, IJ28          ♦Small chip area required for ♦Pigmented        inks may be infeasible, as ♦IJ29, IJ30, IJ31, IJ32               each actuator pigment particles may jam the bend ♦       IJ33, IJ34, IJ35, IJ36          ♦Fast operation actuator ♦IJ37, IJ38,      IJ39, IJ40          ♦High efficiency  ♦IJ41          ♦CMOS compatible voltages          and currents          ♦Standard MEMS processes          can be used          ♦Easy extension from single          nozzles to pagewidth print          heads        High CTE A material with a very high ♦High force can be      generated ♦Requires special material (e.g. PTFE) .diamond-s       olid.IJ09, IJ17, IJ18, IJ20        thermoelastic coefficient of thermal expansion ♦PTFE is      a candidate for low ♦Requires a PTFE deposition process,      ♦IJ21, IJ22, IJ23, IJ24        actuator (CTE) such as dielectric constant which is not yet standard      in ULSI fabs ♦IJ27, IJ28, IJ29, IJ30         polytetrafluoroethylene (PTFE) is insulation in ULSI ♦PT       FE deposition cannot be followed ♦IJ31, IJ42, IJ43, IJ44         used. As high CTE materials are ♦Very low power with      high temperature (above 350°       C.)                                    usually non-conductive, a heater        consumption processing         fabricated from a conductive material ♦Many ink types      can be used ♦Pigmented inks may be infeasible, as         is incorporated. A 50 μm long PTFE ♦Simple planar      fabrication pigment particles may jam the bend         bend actuator with polysilicon heater ♦Small chip area      required for actuator         and 15 mW power input can provide each actuator         180 μN force and 10 μm deflection. ♦Fast operation         Actuator motions include: ♦High efficiency         1) Bend ♦CMOS compatible voltages         2) Push and currents         3) Buckle ♦Easy extension from single         4) Rotate nozzles to pagewidth print          heads        Conductive A polymer with a high coefficient of ♦High      force can be generated ♦Requires special materials      development ♦IJ24        polymer thermal expansion (such as PTFE) is ♦Very low      power (High CTE conductive polymer)        thermoelastic doped with conducting substances to consumption .diamond-       solid.Requires a PTFE deposition process,        actuator increase its conductivity to about 3 ♦Many ink      types can be used which is not yet standard in ULSI fabs         orders of magnitude below that of ♦Simple planar      fabrication ♦PTFE deposition cannot be followed         copper. The conducting polymer ♦Small chip area      required for with high temperature (above 350°       C.)                  expands when resistively heated. each actuator      processing         Examples of conducting dopants ♦Fast operation .diamond-       solid.Evaporation and CVD deposition         include: ♦High efficiency techniques cannot be used            1) Carbon nanotubes ♦CMOS compatible voltages      ♦Pigmented inks may be infeasible, as         2) Metal fibers and currents pigment particles may jam the bend              3) Conductive polymers such as ♦Easy extension      from single actuator         doped polythiophene nozzles to pagewidth print         4) Carbon granules heads        Shape memory A shape memory alloy such as TiNi ♦High      force is available ♦Fatigue limits maximum number of      ♦IJ26        alloy (also known as Nitinol - Nickel (stresses of hundreds of cycles         Titanium alloy developed at the MPa) ♦Low strain (1%)      is required to extend         Naval Ordnance Laboratory) is ♦Large strain is available        fatigue resistance         thermally switched between its weak (more than 3%) ♦Cycl       e rate limited by heat removal         martensitic state and its high stiffness ♦High corrosion        resistance ♦Requires unusual materials (TiNi)         austenic state. The shape of the ♦Simple construction      ♦The latent heat of transformation must         actuator in its martensitic state is ♦Easy extension      from single be provided         deformed relative to the austenic nozzles to pagewidth print .diamond-       solid.High current operation         shape. The shape change causes heads ♦Requires pre-stres       sing to distort the         ejection of a drop. ♦Low voltage operation martensitic      state        Linear Linear magnetic actuators include the ♦Linear      Magnetic actuators ♦Requires unusual semiconductor      ♦IJ12        Magnetic Linear Induction Actuator (LIA), can be constructed with      materials such as soft magnetic alloys        Actuator Linear Permanent Magnet high thrust, long travel, and (e.g.      CoNiFe [1])         Synchronous Actuator (LPMSA), high efficiency using planar .diamond-so       lid.Some varieties also require permanent         Linear Reluctance Synchronous semiconductor fabrication magnetic      materials such as         Actuator (LRSA), Linear Switched techniques Neodymium iron boron      (NdFeB)         Reluctance Actuator (LSRA), and the ♦Long actuator      travel is ♦Requires complex multi-phase drive         Linear Stepper Actuator (LSA). available circuitry          ♦Medium force is available ♦High current        operation          ♦Low voltage operation

       - BASIC OPERATION MODE        Operational        mode Description Advantages Disadvantages Examples        Actuator This is the simplest mode of ♦Simple operation      ♦Drop repetition rate is usually limited ♦The       rmal inkjet        directly operation: the actuator directly ♦No external      fields required to less than 10 KHz. However, this is ♦Piez       oelectric inkjet        pushes ink supplies sufficient kinetic energy to ♦Satelli       te drops can be not fundamental to the method, but is ♦IJ0       1, IJ02, IJ03, IJ04         expel the drop. The drop must have a avoided if drop velocity is      related to the refill method normally ♦IJ05, IJ06, IJ07,      IJ09         sufficient velocity to overcome the less than 4 m/s used .diamond-soli       d.IJ11, IJ12, IJ14, IJ16         surface tension. ♦Can be efficient, depending .diamond-s       olid.All of the drop kinetic energy must be ♦IJ20, IJ22,      IJ23, IJ24          upon the actuator used provided by the actuator ♦IJ25,        IJ26, IJ27, IJ28           ♦Satellite drops usually form if drop ♦I       J29, IJ30, IJ31, IJ32           velocity is greater than 4.5 m/s ♦IJ33, IJ34, IJ35,      IJ36            ♦IJ37, IJ38, IJ39, IJ40            ♦IJ41, IJ42, IJ43, IJ44        Proximity The drops to be printed are selected ♦Very      simple print head ♦Requires close proximity between the      ♦Silverbrook, EP 0771         by some manner (e.g. thermally fabrication can be used print head and        the print media or 658 A2 and related         induced surface tension reduction of ♦The drop selection        means transfer roller patent applications         pressurized ink). Selected drops are does not need to provide the      ♦May require two print heads printing         separated from the ink in the nozzle energy required to separate      alternate rows of the image         by contact with the print medium or a the drop from the nozzle      ♦Monolithic color print heads are         transfer roller.  difficult        Electrostatic The drops to be printed are selected ♦Very        simple print head ♦Requires very high electrostatic      field ♦Silverbrook, EP 0771        pull on ink by some manner (e.g. thermally fabrication can be used      ♦Electrostatic field for small nozzle 658 A2 and related          induced surface tension reduction of ♦The drop      selection means sizes is above air breakdown patent applications                pressurized ink). Selected drops are does not need to provide      the ♦Electrostatic field may attract dust ♦To       ne-Jet         separated from the ink in the nozzle energy required to separate             by a strong electric field. the drop from the nozzle        Magnetic pull The drops to be printed are selected ♦Very        simple print head ♦Requires magnetic ink ♦S       ilverbrook, EP 0771        on ink by some manner (e.g. thermally fabrication can be used .diamond-       solid.Ink colors other than black are difficult 658 A2 and related             induced surface tension reduction of ♦The drop      selection means ♦Requires very high magnetic fields patent        applications         pressurized ink). Selected drops are does not need to provide the            separated from the ink in the nozzle energy required to separate          by a strong magnetic field acting on the drop from the nozzle               the magnetic ink.        Shutter The actuator moves a shutter to block ♦High      speed (>50 KHz) ♦Moving parts are required ♦I       J13, IJ17, IJ21         ink flow to the nozzle. The ink operation can be achieved .diamond-sol       id.Requires ink pressure modulator         pressure is pulsed at a multiple of the due to reduced refill time      ♦Friction and wear must be considered         drop ejection frequency. ♦Drop timing can be very      ♦Stiction is possible          accurate          ♦The actuator energy can be          very low        Shuttered grill The actuator moves a shutter to block ♦Ac       tuators with small travel ♦Moving parts are required      ♦IJ08, IJ15, IJ18, IJ19         ink flow through a grill to the nozzle. can be used ♦Req       uires ink pressure modulator         The shutter movement need only be ♦Actuators with small        force ♦Friction and wear must be considered         equal to the width of the grill holes. can be used ♦Stic       tion is possible          ♦High speed (>50 KHz)          operation can be achieved        Pulsed A pulsed magnetic field attracts an ♦Extremely      low energy ♦Requires an external pulsed magnetic .diamond-s       olid.IJ10        magnetic pull `ink pusher` at the drop ejection operation is possible      field        on ink pusher frequency. An actuator controls a ♦No heat        dissipation ♦Requires special materials for both the            catch, which prevents the ink pusher problems actuator and the ink        pusher         from moving when a drop is not to  ♦Complex construction         be ejected.

       - AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES)        Auxiliary        Mechanism Description Advantages Disadvantages Examples        None The actuator directly fires the ink ♦Simplicity of      construction ♦Drop ejection energy must be supplied      ♦Most inkjets,         drop, and there is no external field or ♦Simplicity of      operation by individual nozzle actuator including         other mechanism required. ♦Small physical size      piezoelectric and            thermal bubble.            ♦IJ01- IJ07, IJ09, IJ11            ♦IJ12, IJ14, IJ20, IJ22            ♦IJ23-IJ45        Oscillating ink The ink pressure oscillates, providing ♦O       scillating ink pressure can ♦Requires external ink      pressure ♦Silverbrook, EP 0771        pressure much of the drop ejection energy. provide a refill pulse,      oscillator 658 A2 and related        (including The actuator selects which drops are allowing higher      operating ♦Ink pressure phase and amplitude must patent      applications        acoustic to be fired by selectively blocking or speed be carefully      controlled ♦IJ08, IJ13, IJ15, IJ17        stimulation) enabling nozzles. The ink pressure ♦The      actuators may operate ♦Acoustic reflections in the ink      chamber ♦IJ18, IJ19, IJ21         oscillation may be achieved by with much lower energy must be      designed for         vibrating the print head, or preferably ♦Acoustic      lenses can be used         by an actuator in the ink supply. to focus the sound on the          nozzles        Media The print head is placed in close ♦Low power      ♦Precision assembly required ♦Silverbrook,      EP 0771        proximity proximity to the print medium. ♦High accuracy      ♦Paper fibers may cause problems 658 A2 and related               Selected drops protrude from the ♦Simple print      head ♦Cannot print on rough substrates patent applications         print head further than unselected construction         drops, and contact the print medium.         The drop soaks into the medium fast         enough to cause drop separation.        Transfer roller Drops are printed to a transfer roller ♦H       igh accuracy ♦Bulky ♦Silverbrook, EP 0771          instead of straight to the print ♦Wide range of print      ♦Expensive 658 A2 and related         medium. A transfer roller can also be substrates can be used .diamond-       solid.Complex construction patent applications         used for proximity drop separation. ♦Ink can be dried      on the  ♦Tektronix hot melt          transfer roller  piezoelectric inkjet            ♦Any of the IJ series        Electrostatic An electric field is used to accelerate ♦Lo       w power ♦Field strength required for separation .diamond-s       olid.Silverbrook, EP 0771         selected drops towards the print ♦Simple print head of      small drops is near or above air 658 A2 and related         medium. construction breakdown patent applications            ♦Tone-Jet        Direct A magnetic field is used to accelerate ♦Low power        ♦Requires magnetic ink ♦Silverbrook, EP      0771        magnetic field selected drops of magnetic ink ♦Simple      print head ♦Requires strong magnetic field 658 A2 and      related         towards the print medium. construction  patent applications        Cross The print head is placed in a constant ♦Does not      require magnetic ♦Requires external magnet ♦I       J06, IJ16        magnetic field magnetic field. The Lorenz force in a materials to be      integrated in ♦Current densities may be high,         current carrying wire is used to move the print head resulting in      electromigration problems         the actuator. manufacturing process        Pulsed A pulsed magnetic field is used to ♦Very low      power operation is ♦Complex print head construction      ♦IJ10        magnetic field cyclically attract a paddle, which possible .diamond-sol       id.Magnetic materials required in print         pushes on the ink. A small actuator ♦Small print head      size head         moves a catch, which selectively         prevents the paddle from moving.

       - ACTUATOR AMPLIFICATION OR MODIFICATION METHOD        Actuator        amplification Description Advantages Disadvantages Examples        None No actuator mechanical amplification ♦Operational      simplicity ♦Many actuator mechanisms have ♦Th       ermal Bubble         is used. The actuator directly drives  insufficient travel, or      insufficient force, Inkjet         the drop ejection process.  to efficiently drive the drop ejection      ♦IJ01, IJ02, IJ06, IJ07           process ♦IJ16, IJ25, IJ26        Differential An actuator material expands more ♦Provides        greater travel in a ♦High stresses are involved .diamond-       solid.Piezoelectric        expansion on one side than on the other. The reduced print head area      ♦Care must be taken that the materials ♦IJ03,        IJ09, IJ17-IJ24        bend actuator expansion may be thermal, ♦The bend      actuator converts do not delaminate ♦IJ27, IJ29-IJ39,      IJ42,         piezoelectric, magnetostrictive, or a high force low travel .diamond-s       olid.Residual bend resulting from high ♦IJ43, IJ44               other mechanism. actuator mechanism to high temperature or high        stress during          travel, lower force formation          mechanism.        Transient bend A trilayer bend actuator where the ♦Very      good temperature ♦High stresses are involved .diamond-solid       .IJ40, IJ41        actuator two outside layers are identical. This stability .diamond-soli       d.Care must be taken that the materials         cancels bend due to ambient ♦High speed, as a new drop      do not delaminate         temperature and residual stress. The can be fired before heat                actuator only responds to transient dissipates         heating of one side or the other. ♦Cancels residual      stress of          formation        Actuator stack A series of thin actuators are stacked. ♦I       ncreased travel ♦Increased fabrication complexity      ♦Some piezoelectric         This can be appropriate where ♦Reduced drive voltage      ♦Increased possibility of short circuits ink jets         actuators require high electric field  due to pinholes ♦       IJ04         strength, such as electrostatic and         piezoelectric actuators.        Multiple Multiple smaller actuators are used ♦Increases      the force available ♦Actuator forces may not add linearly,        ♦IJ12, IJ13, IJ18, IJ20        actuators simultaneously to move the ink. Each from an actuator      reducing efficiency ♦IJ22, IJ28, IJ42, IJ43         actuator need provide only a portion ♦Multiple actuators        can be         of the force required. positioned to control ink          flow accurately        Linear Spring A linear spring is used to transform a ♦Mat       ches low travel actuator ♦Requires print head area for      the spring ♦IJ15         motion with small travel and high with higher travel         force into a longer travel, lower force requirements         motion. ♦Non-contact method of          motion transformation        Reverse spring The actuator loads a spring. When ♦Better        coupling to the ink ♦Fabrication complexity .diamond-soli       d.IJ05, IJ11         the actuator is turned off, the spring  ♦High stress in        the spring         releases. This can reverse the         force/distance curve of the actuator         to make it compatible with the         force/time requirements of the drop         ejection.        Coiled A bend actuator is coiled to provide ♦Increases      travel ♦Generally restricted to planar ♦IJ17,        IJ21, IJ34, IJ35        actuator greater travel in a reduced chip area. ♦Reduces        chip area implementations due to extreme          ♦Planar implementations are fabrication difficulty in      other          relatively easy to fabricate. orientations.        Flexure bend A bend actuator has a small region ♦Simple      means of increasing ♦Care must be taken not to exceed the      ♦IJ10, IJ19, IJ33        actuator near the fixture point, which flexes travel of a bend      actuator elastic limit in the flexure area         much more readily than the  ♦Stress distribution is      very uneven         remainder of the actuator. The  ♦Difficult to accurately        model with finite         actuator flexing is effectively  element analysis         converted from an even coiling to an         angular bend, resulting in greater         travel of the actuator tip.        Gears Gears can be used to increase travel ♦Low force,      low travel ♦Moving parts are required ♦IJ13         at the expense of duration. Circular actuators can be used .diamond-so       lid.Several actuator cycles are required         gears, rack and pinion, ratchets, and ♦Can be fabricated        using ♦More complex drive electronics         other gearing methods can be used. standard surface MEMS .diamond-soli       d.Complex construction          processes ♦Friction, friction, and wear are possible         Catch The actuator controls a small catch. ♦Very low      actuator energy ♦Complex construction ♦IJ10         The catch either enables or disables ♦Very small      actuator size ♦Requires external force         movement of an ink pusher that is  ♦Unsuitable for      pigmented inks         controlled in a bulk manner.        Buckle plate A buckle plate can be used to change ♦Very      fast movement ♦Must stay within elastic limits of the      ♦S. Hirata et al, "An         a slow actuator into a fast motion. It achievable materials for long      device life Ink-jet Head . . . ",         can also convert a high force, low  ♦High stresses      involved Proc. IEEE MEMS,         travel actuator into a high travel,  ♦Generally high      power requirement Feb. 1996, pp 418-         medium force motion.   423.            ♦IJ18, IJ27        Tapered A tapered magnetic pole can increase ♦Linearizes        the magnetic ♦Complex construction ♦IJ14         magnetic pole travel at the expense of force. force/distance curve          Lever A lever and fulcrum is used to ♦Matches low      travel actuator ♦High stress around the fulcrum .diamond-so       lid.IJ32, IJ36, IJ37         transform a motion with small travel with higher travel         and high force into a motion with requirements         longer travel and lower force. The ♦Fulcrum area has no        linear         lever can also reverse the direction of movement, and can be used            travel. for a fluid seal        Rotary The actuator is connected to a rotary ♦High      mechanical advantage ♦Complex construction ♦I       J28        impeller impeller. A small angular deflection ♦The ratio        of force to travel ♦Unsuitable for pigmented inks               of the actuator results in a rotation of of the actuator can be         the impeller vanes, which push the matched to the nozzle         ink against stationary vanes and out requirements by varying the             of the nozzle. number of impeller vanes        Acoustic lens A refractive or diffractive (e.g. zone ♦No        moving parts ♦Large area required ♦1993      Hadimioglu et         plate) acoustic lens is used to  ♦Only relevant for      acoustic ink jets al, EUP 550,192         concentrate sound waves.   ♦1993 Elrod et al, EUP                 572,220        Sharp A sharp point is used to concentrate ♦Simple      construction ♦Difficult to fabricate using standard      ♦Tone-jet        conductive an electrostatic field.  VLSI processes for a surface      ejecting        point   ink-jet           ♦Only relevant for electrostatic ink jets

       - ACTUATOR MOTION        Actuator        motion Description Advantages Disadvantages Examples        Volume The volume of the actuator changes, ♦Simple      construction in the ♦High energy is typically required to      ♦Hewlett-Packard        expansion pushing the ink in all directions. case of thermal ink jet      achieve volume expansion. This leads Thermal Inkjet           to thermal stress, cavitation, and ♦Canon Bubblejet            kogation in thermal ink jet           implementations        Linear, normal The actuator moves in a direction ♦Efficie       nt coupling to ink ♦High fabrication complexity may be      ♦IJ01, IJ02, IJ04, IJ07        to chip surface normal to the print head surface. The drops ejected      normal to the required to achieve perpendicular ♦IJ11,      IJ14         nozzle is typically in the line of surface motion         movement.        Linear, parallel The actuator moves parallel to the ♦Suit       able for planar ♦Fabrication complexity ♦IJ1       2, IJ13, IJ15, IJ33        to chip surface print head surface. Drop ejection fabrication .diamond-       solid.Friction ♦IJ34, IJ35, IJ36         may still be normal to the surface.  ♦Striction               Membrane An actuator with a high force but ♦The      effective area of the ♦Fabrication complexity .diamond-soli       d.1982 Howkins USP        push small area is used to push a stiff actuator becomes the .diamond-s       olid.Actuator size 4,459,601         membrane that is in contact with the membrane area ♦Diff       iculty of integration in a VLSI         ink.  process        Rotary The actuator causes the rotation of ♦Rotary      levers may be used ♦Device complexity ♦IJ05,        IJ08, IJ13, IJ28         some element, such a grill or to increase travel ♦May      have friction at a pivot point         impeller ♦Small chip area          requirements        Bend The actuator bends when energized. ♦A very small      change in ♦Requires the actuator to be made from  .diamond-       solid.1970 Kyser et al USP         This may be due to differential dimensions can be at least two      distinct layers; or to have a 3,946,398         thermal expansion, piezoelectric converted to a large motion. thermal        difference across the actuator ♦1973 Stemme USP         expansion, magnetostriction, or other   3,747,120         form of relative dimensional change.   ♦IJ03, IJ09,      IJ10, IJ19            ♦IJ23, IJ24, IJ25, IJ29            ♦IJ30, IJ31, IJ33, IJ34            ♦IJ35        Swivel The actuator swivels around a central ♦Allows      operation where the ♦Inefficient coupling to the ink      motion ♦IJ06         pivot. This motion is suitable where net linear force on the         there are opposite forces applied to paddle is zero         opposite sides of the paddle, e.g. ♦Small chip area            Lorenz force. requirements        Straighten The actuator is normally bent, and ♦Can be      used with shape ♦Requires careful balance of stresses to      ♦IJ26, IJ32         straightens when energized. memory alloys where the ensure that the      quiescent bend is          austenic phase is planar accurate        Double bend The actuator bends in one direction ♦One      actuator can be used to ♦Difficult to make the drops      ejected by ♦IJ36, IJ37, IJ38         when one element is energized, and power two nozzles. both bend      directions identical.         bends the other way when another ♦Reduced chip size.      ♦A small efficiency loss compared to         element is energized. ♦Not sensitive to ambient      equivalent single bend actuators.          temperature        Shear Energizing the actuator causes a ♦Can increase the        effective ♦Not readily applicable to other actuator      ♦1985 Fishbeck USP         shear motion in the actuator material. travel of piezoelectric      mechanisms 4,584,590          actuators        Radial The actuator squeezes an ink ♦Relatively easy to      fabricate ♦High force required ♦1970 Zoltan      USP        constriction reservoir, forcing ink from a single nozzles from glass      ♦Inefficient 3,683,212         constricted nozzle. tubing as macroscopic ♦Difficult to        integrate with VLSI          structures processes        Coil/uncoil A coiled actuator uncoils or coils ♦Easy to      fabricate as a planar ♦Difficult to fabricate for non-plana       r ♦IJ17, IJ21, IJ34, IJ35         more tightly. The motion of the free VLSI process devices         end of the actuator ejects the ink. ♦Small area      required, ♦Poor out-of-plane stiffness          therefore low cost        Bow The actuator bows (or buckles) in the ♦Can increase      the speed of ♦Maximum travel is constrained ♦       IJ16, IJ18, IJ27         middle when energized. travel ♦High force required              ♦Mechanically rigid        Push-Pull Two actuators control a shutter. One ♦The      structure is pinned at ♦Not readily suitable for inkjets      which ♦IJ18         actuator pulls the shutter, and the both ends, so has a high out-      directly push in ink         other pushes it. of-plane rigidity        Curl inwards A set of actuators curl inwards to ♦Good      fluid flow to the ♦Design complexity ♦IJ20,      IJ42         reduce the volume of ink that they region behind the actuator                enclose. increases efficiency        Curl outwards A set of actuators curl outwards, ♦Relative       ly simple ♦Relatively large chip area ♦IJ43         pressurizing ink in a chamber construction         surrounding the actuators, and         expelling ink from a nozzle in the         chamber.        Iris Multiple vanes enclose a volume of ♦High efficiency        ♦High fabrication complexity ♦IJ22                ink. These simultaneously rotate, ♦Small chip      area ♦Not suitable for pigmented inks         reducing the volume between the         vanes.        Acoustic The actuator vibrates at a high ♦The actuator      can be ♦Large area required for efficient ♦19       93 Hadimioglu et        vibration frequency. physically distant from the operation at useful      frequencies al, EUP 550,192          ink ♦Acoustic coupling and crosstalk ♦199       3 Elrod et al, EUP           ♦Complex drive circuitry 572,220           ♦Poor control of drop volume and           position        None In various ink jet designs the actuator ♦No moving      parts ♦Various other tradeoffs are required to .diamond-sol       id.Silverbrook, EP 0771         does not move.  eliminate moving parts 658 A2 and related            patent applications           ♦Tone-jet

    __________________________________________________________________________     NOZZLE REFILL METHOD                                                           Nozzle                                                                           refill                                                                         method Description Advantages Disadvantages Examples                         __________________________________________________________________________     Surface                                                                             After the actuator is energized, it                                                             ♦Fabrication simplicity                                                       ♦Low speed                                                                         ♦Therma                                                          l inkjet                    tension typically returns rapidly to its normal ♦Operation                                                          al simplicity                                                                  ♦Surfac                                                          e tension force                                                                relatively small                                                               ♦Piezoe                                                          lectric inkjet                                                                   position. This                                                               rapid return sucks                                                             in  compared to                                                                actuator force                                                                 ♦IJ01-I                                                          J07, IJ10-IJ14                                                                   air through the                                                              nozzle opening. The                                                            ♦Long                                                            refill time usually                                                            dominates the                                                                  ♦IJ16,                                                           IJ20, IJ22-IJ45                                                                  ink surface                                                                  tension at the                                                                 nozzle then  total                                                             repetition rate                                                                  exerts a small                                                               force restoring the                                                              meniscus to a                                                                minimum area.                                                                   Shuttered Ink to                                                              the nozzle chamber                                                             is ♦Hig                                                          h speed .diamond-soli                                                          d.Requires common                                                              ink pressure                                                                   ♦IJ08,                                                           IJ13, IJ15, IJ17                                                                oscillating                                                                   provided at a                                                                  pressure that                                                                  oscillates .diamond-s                                                          olid.Low actuator                                                              energy, as the                                                                 oscillator .diamond-s                                                          olid.IJ18, IJ19,                                                               IJ21                        ink at twice the drop ejection frequency. actuator need only open or                                                              ♦May                                                             not be suitable for                                                            pigmented inks                                                                  pressure When a                                                               drop is to be                                                                  ejected, the close                                                             the shutter, instead                                                           of                           shutter is opened for 3 half cycles: ejecting the ink drop                     drop ejection, actuator return, and                                            refill.                                                                       Refill After the main actuator has ejected a ♦High speed,                                                           as the nozzle is                                                               ♦Requir                                                          es two independent                                                             actuators per                                                                  ♦IJ09                                                             actuator drop a                                                               second (refill)                                                                actuator is actively                                                           refilled nozzle                                                                  energized. The                                                               refill actuator                                                                pushes                       ink into the nozzle chamber. The                                               refill actuator returns slowly, to                                             prevent its return from emptying the                                           chamber again.                                                                Positive The ink is held a slight positive ♦High refill                                                             rate, therefore a                                                              ♦Surfac                                                          e spill must be                                                                prevented .diamond-so                                                          lid.Silverbrook,                                                                ink pressure. After                                                           the ink drop is high                                                           drop repetition rate                                                           is ♦Hig                                                          h hydrophobic print                                                            head surfaces EP                                                               0771                        pressure ejected, the nozzle chamber fills possible are required 658 A2                                                           and related                  quickly as surface tension and ink   patent applications                       pressure both operate to refill the   ♦Alternative for                                                               nozzle.   .diamond-                                                          solid.IJ01-IJ07,                                                               IJ10-IJ14                       ♦IJ16, IJ20, IJ22-IJ45                                     __________________________________________________________________________

       - METHOD OF RESTRICTING BACK-FLOW THROUGH INLET        Inlet back-flow        restriction        method Description Advantages Disadvantages Examples        Long inlet The ink inlet channel to the nozzle ♦Design      simplicity ♦Restricts refill rate ♦Thermal      inkjet        channel chamber is made long and relatively ♦Operational        simplicity ♦May result in a relatively large chip      ♦Piezoelectric inkjet         narrow, relying on viscous drag to ♦Reduces crosstalk      area ♦IJ42, IJ43         reduce inlet back-flow.  ♦Only partially effective            Positive ink The ink is under a positive pressure, ♦D       rop selection and ♦Requires a method (such as a nozzle      ♦Silverbrook, EP 0771        pressure so that in the quiescent state some of separation forces can      be rim or effective hydrophobizing, or 658 A2 and related         the ink drop already protrudes from reduced both) to prevent flooding        of the patent applications         the nozzle. ♦Fast refill time ejection surface of the      print head. ♦Possible operation of         This reduces the pressure in the   the following:         nozzle chamber which is required to   ♦IJ01-IJ07,      IJ09-IJ12         eject a certain volume of ink. The   ♦IJ14, IJ16, IJ20,        IJ22,         reduction in chamber pressure results   ♦IJ23-IJ34,      IJ36-IJ41         in a reduction in ink pushed out   ♦IJ44         through the inlet.        Baffle One or more baffles are placed in the ♦The refill        rate is not as ♦Design complexity ♦HP      Thermal Ink Jet         inlet ink flow. When the actuator is restricted as the long inlet      ♦May increase fabrication complexity ♦Tektron       ix         energized, the rapid ink movement method. (e.g. Tektronix hot melt      Piezoelectric piezoelectric ink jet         creates eddies which restrict the flow ♦Reduces      crosstalk print heads).         through the inlet. The slower refill         process is unrestricted, and does not         result in eddies.        Flexible flap In this method recently disclosed by ♦Signi       ficantly reduces back- ♦Not applicable to most inkjet      ♦Canon        restricts inlet Canon, the expanding actuator flow for edge-shooter      configurations         (bubble) pushes on a flexible flap thermal ink jet devices .diamond-so       lid.Increased fabrication complexity         that restricts the inlet.  ♦Inelastic deformation of      polymer flap           results in creep over extended use        Inlet filter A filter is located between the ink ♦Additio       nal advantage of ink ♦Restricts refill rate .diamond-solid       .IJ04, IJ12, IJ24, IJ27         inlet and the nozzle chamber. The filtration ♦May      result in complex construction ♦IJ29, IJ30         filter has a multitude of small holes ♦Ink filter may      be fabricated         or slots, restricting ink flow. The with no additional process               filter also removes particles which steps         may block the nozzle.        Small inlet The ink inlet channel to the nozzle ♦Design      simplicity ♦Restricts refill rate ♦IJ02,      IJ37, IJ44        compared to chamber has a substantially smaller  ♦May      result in a relatively large chip        nozzle cross section than that of the nozzle,  area         resulting in easier ink egress out of  ♦Only partially      effective         the nozzle than out of the inlet.        Inlet shutter A secondary actuator controls the ♦Increase       s speed of the ink- ♦Requires separate refill actuator      and ♦IJ09         position of a shutter, closing off the jet print head operation drive        circuit         ink inlet when the main actuator is         energized.        The inlet is The method avoids the problem of ♦Back-flow        problem is ♦Requires careful design to minimize .diamond-       solid.IJ01, IJ03, IJ05, IJ06        located behind inlet back-flow by arranging the ink- eliminated the      negative pressure behind the paddle ♦IJ07, IJ10, IJ11,      IJ14        the ink- pushing surface of the actuator   ♦IJ16, IJ22,      IJ23, IJ25        pushing between the inlet and the nozzle.   ♦IJ28, IJ31,        IJ32, IJ33        surface    ♦IJ34, IJ35, IJ36, IJ39            ♦IJ40, IJ41        Part of the The actuator and a wall of the ink ♦Significa       nt reductions in ♦Small increase in fabrication .diamond-s       olid.IJ07, IJ20, IJ26, IJ38        actuator chamber are arranged so that the back-flow can be achieved      complexity        moves to shut motion of the actuator closes off the ♦Comp       act designs possible        off the inlet inlet.        Nozzle In some configurations of ink jet, ♦Ink back-flow        problem is ♦None related to ink back-flow on .diamond-sol       id.Silverbrook, EP 0771        actuator does there is no expansion or movement eliminated actuation      658 A2 and related        not result in of an actuator which may cause ink   patent applications        ink back-flow back-flow through the inlet.   ♦Valve-jet            ♦Tone-jet            ♦IJ08, IJ13, IJ15, IJ17            ♦IJ18, IJ19, IJ21

       - NOZZLE CLEARING METHOD        Nozzle        Clearing        method Description Advantages Disadvantages Examples        Normal nozzle All of the nozzles are fired ♦No added      complexity on the ♦May not be sufficient to displace dried        ♦Most ink jet systems        firing periodically, before the ink has a print head ink .diamond-solid       .IJ01-IJ07, IJ09-IJ12         chance to dry. When not in use the   ♦IJ14, IJ16, IJ20,        IJ22         nozzles are sealed (capped) against   ♦IJ23-IJ34,      IJ36-IJ45         air.         The nozzles firing is usually         performed during a special clearing         cycle, after first moving the print         head to a cleaning station.        Extra power to In systems which heat the ink, but do ♦Can        be highly effective if ♦Requires higher drive voltage      for ♦Silverbrook, EP 0771        ink heater not boil it under normal situations, the heater is adjacent        to the clearing 658 A2 and related         nozzle clearing can be achieved by nozzle ♦May require      larger drive transistors patent applications         over-powering the heater and boiling         ink at the nozzle.        Rapid The actuator is fired in rapid ♦Does not require      extra drive ♦Effectiveness depends substantially .diamond-s       olid.May be used with:        succession of succession. In some configurations, circuits on the      print head upon the configuration of the inkjet ♦IJ01-IJ07,        IJ09-IJ11        actuator this may cause heat build-up at the ♦Can be      readily controlled nozzle ♦IJ14, IJ16, IJ20, IJ22        pulses nozzle which boils the ink, clearing and initiated by digital      logic  ♦IJ23-IJ25, IJ27-IJ34         the nozzle. In other situations, it may   ♦IJ36-IJ45           cause sufficient vibrations to         dislodge clogged nozzles.        Extra power to Where an actuator is not normally ♦A      simple solution where ♦Not suitable where there is a hard      limit ♦May be used with:        ink pushing driven to the limit of its motion, applicable to actuator      movement ♦IJ03, IJ09, IJ16, IJ20        actuator nozzle clearing may be assisted by   ♦IJ23,      IJ24, IJ25, IJ27         providing and enhanced drive signal to   ♦IJ29, IJ30,      IJ31, IJ32         the actuator.   ♦IJ39, IJ40, IJ41, IJ42            ♦IJ43, IJ44, IJ45        Acoustic An ultrasonic wave is applied to the ♦A high      nozzle clearing ♦High implementation cost if system      ♦IJ08, IJ13, IJ15, IJ17        resonance ink chamber. This wave is of an capability can be achieved      does not already include an acoustic ♦IJ18, IJ19, IJ21            appropriate amplitude and frequency ♦May be implement       ed at actuator         to cause sufficient force at the nozzle very low cost in systems             to clear blockages. This is easiest to which already include             achieve if the ultrasonic wave is at a acoustic actuators                resonant frequency of the ink cavity.        Nozzle A microfabricated plate is pushed ♦Can clear      severely clogged ♦Accurate mechanical alignment is      ♦Silverbrook, EP 0771        clearing plate against the nozzles. The plate has a nozzles required      658 A2 and related         post for every nozzle. The array of  ♦There is risk of      damage to the nozzles         posts  ♦Accurate fabrication is required        Ink pressure The pressure of the ink is temporarily ♦May        be effective where ♦Requires pressure pump or other      ♦May be used with all        pulse increased so that ink streams from all other methods cannot be      pressure actuator IJ series ink jets         of the nozzles. This may be used in used ♦Expensive            conjuction with actuator energizing.  ♦Wasteful of      ink        Print head A flexible `blade`       is wiped across the ♦Effective for planar print .diamond-s       olid.Difficult to use if print head surface is ♦Many ink      jet systems        wiper print head surface. The blade is head surfaces non-planar or      very fragile         usually fabricated from a flexible ♦Low cost .diamond-so       lid.Requires mechanical parts         polymer, e.g. rubber or synthetic  ♦Blade can wear out      in high volume         elastomer.  print systems        Separate ink A separate heater is provided at the ♦Can      be effective where ♦Fabrication complexity ♦C       an be used with        boiling heater nozzle although the normal drop e- other nozzle      clearing  many IJ series ink         ection mechanism does not require it. methods cannot be used  jets           The heaters do not require it. ♦Can be implemented at        no         drive circuits, as many nozzles can additional cost in some         be cleared simultaneously, and no inkjet configurations         imaging is required.

       - NOZZLE PLATE CONSTRUCTION        Nozzle plate        construction Description Advantages Disadvantages Examples        Electroformed A nozzle plate is separately ♦Fabrication      simplicity ♦High temperature and pressures are .diamond-sol       id.Hewlett Packard        nickel fabricated from electroformed nickel,  required to bond nozzle      plate Thermal Inkjet         and bonded to the print head chip.  ♦Minimum thickness      constraints           ♦Differential thermal expansion        Laser ablated Individual nozzle holes are ablated ♦No      masks required ♦Each hole must be individually formed      ♦Canon Bubblejet        or drilled by an intense UV laser in a nozzle ♦Can be      quite fast ♦Special equipment required ♦1988        Sercel et al.,        polymer plate, which is typically a polymer ♦Some      control over nozzle ♦Slow where there are many thousands      SPIE, Vol. 998         such as polyimide or polysulphone profile is possible of nozzles per      print head Excimer Beam          ♦Equipment required is ♦May produce thin        burrs at exit holes Applications, pp. 76-          relatively low cost  83            ♦1993 Watanabe et al.,            USP 5,208,604        Silicon micro- A separate nozzle plate is ♦High accuracy        is attainable ♦Two part construction ♦K.      Bean, IEEE        machined micromachined from single crystal  ♦High cost      Transactions on         silicon, and bonded to the print head  ♦Requires      precision alignment Electron Devices,         wafer.  ♦Nozzles may be clogged by adhesive Vol. ED-25,        No. 10,            1978, pp 1185-1195            et al., USP 4,899,181        Glass Fine glass capillaries are drawn from ♦No expensive        equipment ♦Very small nozzle sizes are difficult to      ♦1970 Zoltan USP        capillaries glass tubing. This method has been required form 3,683,212         used form making individual nozzles, ♦Simple to make      single ♦Not suited for mass production         but is difficult to use for bulk nozzles         manufacturing of print heads with         thousands of nozzles.        Monolithic, The nozzle plate is deposited as a ♦High      accuracy (<1 μm) ♦Requires sacrificial layer under the      ♦Silverbrook, EP 0771        surface micro- layer using standard VLSI deposition ♦Mono       lithic nozzle plate to form the nozzle 658 A2 and related        machined techniques. Nozzles are etched in the ♦Low cost        chamber patent applications        using VLSI nozzle plate using VLSI lithography ♦Existing        processes can be ♦Surface may be fragile to the touch      ♦IJ01, IJ02, IJ04, IJ11        lithographic and etching. used  ♦IJ12, IJ17, IJ18, IJ20        processes    ♦IJ22, IJ24, IJ27, IJ28            ♦IJ29, IJ30, IJ31, IJ32            ♦IJ33, IJ34, IJ36, IJ37            ♦IJ38, IJ39, IJ40, IJ41            ♦IJ42, IJ43, IJ44        Monolithic, The nozzle plate is a buried etch stop ♦High        accuracy (<1 μm) ♦Requires long etch times .diamond-so       lid.IJ03, IJ05, IJ06, IJ07        etched in the wafer. Nozzle chambers are ♦Monolithic      ♦Requires a support wafer ♦IJ08, IJ09, IJ10,        IJ13        through etched in the front of the wafer, and ♦Low cost        ♦IJ14, IJ15, IJ16, IJ19        substrate the wafer is thinned from the back ♦No      differential expansion  ♦IJ21, IJ23, IJ25, IJ26         side. Nozzles are then etched in the         etch stop layer.        No nozzle Various methods have been tried to ♦No nozzles        to become ♦Difficult to control drop position .diamond-so       lid.Ricoh 1995 Sekiya et        plate eliminate the nozzles entirely, to clogged accurately al USP      5,412,413         prevent nozzle clogging. These  ♦Crosstalk problems      ♦1993 Hadimioglu et         include thermal bubble mechanisms   al EUP 550,192         and acoustic lens mechanisms   ♦1993 Elrod et al EUP              572,220        Trough Each drop ejector has a trough ♦Reduced manufactur       ing ♦Drop firing direction is sensitive to ♦       IJ35         through which a paddle moves. complexity wicking.         There is no nozzle plate. ♦Monolithic        Nozzle slit The elimination of nozzle holes and ♦No      nozzles to become ♦Difficult to control drop position      ♦1989 Saito et al USP        instead of replacement by a slit encompassing clogged accurately      4,799,068        individual many actuator positions reduces  ♦Crosstalk      problems        nozzles nozzle clogging, but increases         crosstalk due to ink surface waves

    __________________________________________________________________________     DROP EJECTION DIRECTION                                                        Ejection                                                                         direction Description Advantages Disadvantages Examples                      __________________________________________________________________________     Edge Ink flow is along the surface of the                                                            ♦Simple construction                                                          ♦Nozzles limited to edge                                                           ♦Canon                                                           Bubblejet                   (`edge chip, and ink drops are ejected from ♦No silicon                                                             etching required                                                               ♦High                                                            resolution is                                                                  difficult 1979 Endo                                                            et al GB                    shooter`) the chip edge. ♦Good heat sinking via .diamond-s                                                          olid.Fast color                                                                printing requires                                                              one print patent                                                               2,007,162                     substrate head per color ♦Xerox heater-in-pit                    ♦Mechanically strong  1990 Hawkins et al                         ♦Ease of chip handing  USP 4,899,181                               ♦Tone-jet                                                    Surface Ink flow is along the surface of the ♦No bulk                                                               silicon etching                                                                ♦Maximu                                                          m ink flow is                                                                  severely .diamond-sol                                                          id.Hewlett-Packard                                                             TIJ                         (`roof chip, and ink drops are ejected from required restricted 1982                                                              Vaught et al                                                                    shooter`) the chip                                                            surface, normal to                                                             the plane .diamond-so                                                          lid.Silicon can make                                                           an  USP 4,490,728                                                                of the chip.                                                                 effective heat sink                                                            ♦IJ02,                                                           IJ11, IJ12, IJ20                                                                  ♦Mec                                                          hanical strength                                                               ♦IJ22                                                             Through Ink flow is                                                           through the chip,                                                              and ink .diamond-soli                                                          d.High ink flow                                                                ♦Requir                                                          es bulk silicon                                                                etching .diamond-soli                                                          d.Silverbrook,                                                                  chip, drops are                                                               ejected from the                                                               front ♦                                                          Suitable for                                                                   pagewidth print  EP                                                            0771                        forward surface of the chip. ♦High nozzle packing density                                                            658 A2 and related                                                             (`up  therefore low                                                            patent applications        shooter`)  manufacturing cost  ♦IJ04, IJ17, IJ17, IJ24                                                                   ♦I                                                          J27-IJ45                    Through Ink flow is through the chip, and ink ♦High ink                                                             flow ♦R                                                          equires wafer                                                                  thinning .diamond-sol                                                          id.IJ01, IJ03, IJ05,                                                           IJ06                        chip, drops are ejected from the rear ♦Suitable for                                                                 pagewidth print                                                                ♦Requir                                                          es special handling                                                            during .diamond-solid                                                          .IJ07, IJ08, IJ09,                                                             IJ10                        reverse surface of the chip. ♦High nozzle packing density                                                           manufacture .diamond-                                                          solid.IJ13, IJ14,                                                              IJ15, IJ16                  (`down  therefore low  ♦IJ19, IJ21, IJ23, IJ25                   shooter`)  manufacturing cost  ♦IJ26                             Through Ink flow is through the actuator, ♦Suitable for                                                             piezoelectric                                                                  ♦Pagewi                                                          dth print heads                                                                require several                                                                ♦Epson                                                           Stylus                      actuator which is not fabricated as part of the print heads thousand                                                              connections to drive                                                           circuits .diamond-sol                                                          id.Tektronix hot                                                               melt                         same substrate as the drive  ♦Cannot be manufactured in                                                            standard piezoelectri                                                          c ink jets                   transistors.  CMOS fabs                                                          ♦Complex assembly required                                  __________________________________________________________________________

       - INK TYPE        Ink type Description Advantages Disadvantages Examples        Aqueous, dye Water based ink which typically ♦Environment       ally friendly ♦Slow drying ♦Most existing      inkjets         contains: water, dye, surfactant, ♦No odor .diamond-soli       d.Corrosive ♦All IJ series ink jets         humectant, and biocide.  ♦Bleeds on paper .diamond-solid       .Silverbrook, EP 0771         Modern ink dyes have high water-  ♦May strikethrough      658 A2 and related         fastness, light fastness  ♦Cockles paper patent      applications        Aqueous, Water based ink which typically ♦Environmentally        friendly ♦Slow drying ♦IJ02, IJ04, IJ21,      IJ26        pigment contains: water, pigment, surfactant, ♦No odor      ♦Corrosive ♦IJ27, IJ30         humectant, and biocide. ♦Reduced bleed ♦Pi       gment may clog nozzles ♦Silverbrook, EP 0771         Pigments have an advantage in ♦Reduced wicking .diamond-       solid.Pigment may clog actuator mechanisms 658 A2 and related         reduced bleed, wicking and ♦Reduced strikethrough      ♦Cockles paper patent applications         strikethrough.   ♦Piezoelectric ink-jets            ♦Thermal ink jets            (with significant            restrictions)        Methyl Ethyl MEK is a highly volatile solvent used ♦Very        fast drying ♦Odorous ♦All IJ series ink      jets        Ketone (MEK) for industrial printing on difficult ♦Prints        on various substrates ♦Flammable         surfaces such as aluminum cans. such as metals and plastics        Alcohol Alcohol based inks can be used ♦Fast drying      ♦Slight odor ♦All IJ series ink jets               (ethanol, 2- where the printer must operate at ♦Op       erates at sub-freezing ♦Flammable        butanol, and temperatures below the freezing temperatures        others) point of water. An example of this is ♦Reduced      paper cockle         in-camera consumer photographic ♦Low cost         printing.        Phase change The ink is solid at room temperature, ♦No      drying time- ink ♦High viscosity ♦Tektronix      hot melt        (hot melt) and is melted in the print head before instantly freezes on        the print ♦Printed ink typically has a `waxy` feel      piezoelectric ink jets         jetting. Hot melt inks are usually was medium ♦Printed      pages may `block` ♦1989 Nowak USP         based, with a melting point around ♦Almost any print      medium ♦Ink temperature may be above the curie 4,820,346          80° C.. After jetting the ink freezes can be used point of      permanent magnets ♦All IJ series ink jets         almost instantly upon contacting the ♦No paper cockle      occurs ♦Ink heaters consume power         print medium or a transfer roller. ♦No wicking occurs      ♦Long warm-up time          ♦No bleed occurs          ♦No strikethrough occurs        Oil Oil based inks are extensively used ♦High solubility        medium for ♦High viscosity: this is a significant      ♦All IJ series ink jets         in offset printing. They have some dyes limitation for use in      inkjets, which         advantages in improved ♦Does not cockle paper usually      require a low viscosity. Some         characteristics on paper (especially ♦Does not wick      through short chain and multi-branched oils         no wicking or cockle). Oil soluble paper have a sufficiently low      viscosity.         dies and pigments are required.  ♦Slow drying        Microemulsion A microemulsion is a stable, self ♦Stops      ink bleed ♦Viscosity higher than water ♦All      IJ series ink jets         forming emulsion of oil, water, and ♦High dye solubility        ♦Cost is slightly higher than water based         surfactant. The characteristic drop ♦Water, oil, and      amphiphilic ink         size is less than 100 nm, and is soluble dies can be used .diamond-sol       id.High surfactant concentration required         determined by the preferred ♦Can stabilize pigment      (around 5%)         curvature of the surfactant. suspensions

Ink Jet Printing

A large number of new forms of ink jet printers have been developed to facilitate alternative ink jet technologies for the image processing and data distribution system. Various combinations of ink jet devices can be included in printer devices incorporated as part of the present invention. Australian Provisional Patent Applications relating to these ink jets which are specifically incorporated by cross reference include:

    ______________________________________                                         Australian                                                                       Provisional Filing                                                             Number Date Title                                                            ______________________________________                                         PO8066  15-Jul-97                                                                               Image Creation Method and Apparatus (IJ01)                      PO8072 15-Jul-97 Image Creation Method and Apparatus (IJ02)                    PO8040 15-Jul-97 Image Creation Method and Apparatus (IJ03)                    PO8071 15-Jul-97 Image Creation Method and Apparatus (IJ04)                    PO8047 15-Jul-97 Image Creation Method and Apparatus (IJ05)                    PO8035 15-Jul-97 Image Creation Method and Apparatus (IJ06)                    PO8044 15-Jul-97 Image Creation Method and Apparatus (IJ07)                    PO8063 15-Jul-97 Image Creation Method and Apparatus (IJ08)                    PO8057 15-Jul-97 Image Creation Method and Apparatus (IJ09)                    PO8056 15-Jul-97 Image Creation Method and Apparatus (IJ10)                    PO8069 15-Jul-97 Image Creation Method and Apparatus (IJ11)                    PO8049 15-Jul-97 Image Creation Method and Apparatus (IJ12)                    PO8036 15-Jul-97 Image Creation Method and Apparatus (IJ13)                    PO8048 15-Jul-97 Image Creation Method and Apparatus (IJ14)                    PO8070 15-Jul-97 Image Creation Method and Apparatus (IJ15)                    PO8067 15-Jul-97 Image Creation Method and Apparatus (IJ16)                    PO8001 15-Jul-97 Image Creation Method and Apparatus (IJ17)                    PO8038 15-Jul-97 Image Creation Method and Apparatus (IJ18)                    PO8033 15-Jul-97 Image Creation Method and Apparatus (IJ19)                    PO8002 15-Jul-97 Image Creation Method and Apparatus (IJ20)                    PO8068 15-Jul-97 Image Creation Method and Apparatus (IJ21)                    PO8062 15-Jul-97 Image Creation Method and Apparatus (IJ22)                    PO8034 15-Jul-97 Image Creation Method and Apparatus (IJ23)                    PO8039 15-Jul-97 Image Creation Method and Apparatus (IJ24)                    PO8041 15-Jul-97 Image Creation Method and Apparatus (IJ25)                    PO8004 15-Jul-97 Image Creation Method and Apparatus (IJ26)                    PO8037 15-Jul-97 Image Creation Method and Apparatus (IJ27)                    PO8043 15-Jul-97 Image Creation Method and Apparatus (IJ28)                    PO8042 15-Jul-97 Image Creation Method and Apparatus (IJ29)                    PO8064 15-Jul-97 Image Creation Method and Apparatus (IJ30)                    PO9389 15-Jul-97 Image Creation Method and Apparatus (IJ31)                    PO9391 15-Jul-97 Image Creation Method and Apparatus (IJ32)                    PO0888 15-Jul-97 Image Creation Method and Apparatus (IJ33)                    PO0891 15-Jul-97 Image Creation Method and Apparatus (IJ34)                    PO0890 15-Jul-97 Image Creation Method and Apparatus (IJ35)                    PO0873 15-Jul-97 Image Creation Method and Apparatus (IJ36)                    PO0993 15-Jul-97 Image Creation Method and Apparatus (IJ37)                    PO0890 15-Jul-97 Image Creation Method and Apparatus (IJ38)                    PO1398 15-Jul-97 An Image Creation Method and Apparatus                          (IJ39)                                                                       PO2592 15-Jul-97 An Image Creation Method and Apparatus                          (IJ40)                                                                       PO2593 15-Jul-97 Image Creation Method and Apparatus (IJ41)                    PO3991 15-Jul-97 Image Creation Method and Apparatus (IJ42)                    PO3987 15-Jul-97 Image Creation Method and Apparatus (IJ43)                    PO3985 15-Jul-97 Image Creation Method and Apparatus (IJ44)                    PO3983 15-Jul-97 Image Creation Method and Apparatus (IJ45)                  ______________________________________                                    

Ink Jet Manufacturing

Further, the present application may utilize advanced semiconductor fabrication techniques in the construction of large arrays of ink jet printers. Suitable manufacturing techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                       Provisional Filing                                                             Number Date Title                                                            ______________________________________                                         PO7935  15-Jul-97                                                                               A Method of Manufacture of an Image                               Creation Apparatus (IJM01)                                                   PO7936 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM02)                                                   PO7937 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM03)                                                   PO8061 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM04)                                                   PO8054 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM05)                                                   PO8065 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM06)                                                   PO8055 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM07)                                                   PO8053 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM08)                                                   PO8078 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM09)                                                   PO7933 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM10)                                                   PO7950 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM11)                                                   PO7949 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM12)                                                   PO8060 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM13)                                                   PO8059 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM14)                                                   PO8073 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM15)                                                   PO8076 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM16)                                                   PO8075 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM17)                                                   PO8079 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM18)                                                   PO8050 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM19)                                                   PO8052 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM20)                                                   PO7948 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM21)                                                   PO7951 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM22)                                                   PO8074 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM23)                                                   PO7941 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM24)                                                   PO8077 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM25)                                                   PO8058 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM26)                                                   PO8051 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM27)                                                   PO8045 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM28)                                                   PO7952 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM29)                                                   PO8046 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM30)                                                   PO8503 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM30a)                                                  PO9390 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM31)                                                   PO9392 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM32)                                                   PO0889 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM35)                                                   PO0887 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM36)                                                   PO0882 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM37)                                                   PO0874 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM38)                                                   PO1396 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM39)                                                   PO2591 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM40)                                                   PO3989 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM41)                                                   PO3990 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM42)                                                   PO3986 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM43)                                                   PO3984 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM44)                                                   PO3982 15-Jul-97 A Method of Manufacture of an Image                             Creation Apparatus (IJM45)                                                 ______________________________________                                    

Fluid Supply

Further, the present application may utilize an ink delivery system to the ink jet head. Delivery systems relating to the supply of ink to a series of ink jet nozzles are described in the following Australian provisional patent specifications, the disclosure of which are hereby incorporated by cross-reference:

    ______________________________________                                         Australian                                                                       Provisional                                                                    Number Filing Date Title                                                     ______________________________________                                         PO8003     15-Jul-97  Supply Method and Apparatus (F1)                           PO8005 15-Jul-97 Supply Method and Apparatus (F2)                              PO9404 23-Sep-97 A Device and Method (F3)                                    ______________________________________                                    

MEMS Technology

Further, the present application may utilize advanced semiconductor microelectromechanical techniques in the construction of large arrays of ink jet printers. Suitable microelectromechanical techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                       Provisional                                                                    Number Filing Date Title                                                     ______________________________________                                         PO7943     15-Jul-97  A device (MEMS01)                                          PO8006 15-Jul-97 A device (MEMS02)                                             PO8007 15-Jul-97 A device (MEMS03)                                             PO8008  5-Jul-97 A device (MEMS04)                                             PO8010 15-Jul-97 A device (MEMS05)                                             PO8011 15-Jul-97 A device (MEMS06)                                             PO7947 15-Jul-97 A device (MEMS07)                                             PO7945 15-Jul-97 A device (MEMS08)                                             PO7944 15-Jul-97 A device (MEMS09)                                             PO7946 15-Jul-97 A device (MEMS10)                                             PO9393 23-Sep-97 A Device and Method (MEMS11)                                  PP0875 12-Dec-97 A Device (MEMS12)                                             PP0894 12-Dec-97 A Device and Method (MEMS13)                                ______________________________________                                    

IR Technologies

Further, the present application may include the utilization of a disposable camera system such as those described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                       Provisional                                                                    Number Filing Date Title                                                     ______________________________________                                         PP0895  12-Dec-97 An Image Creation Method and Apparatus                           (IR01)                                                                       PP0870 12-Dec-97 A Device and Method (IR02)                                    PP0869 12-Dec-97 A Device and Method (IR04)                                    PP0887 12-Dec-97 Image Creation Method and Apparatus                             (IR05)                                                                       PP0885 12-Dec-97 An Image Production System (IR06)                             PP0884 12-Dec-97 Image Creation Method and Apparatus                             (IR10)                                                                       PP0886 12-Dec-97 Image Creation Method and Apparatus                             (IR12)                                                                       PP0871 12-Dec-97 A Device and Method (IR13)                                    PP0876 12-Dec-97 An Image Processing Method and Apparatus                        (IR14)                                                                       PP0877 12-Dec-97 A Device and Method (IR16)                                    PP0878 12-Dec-97 A Device and Method (IR17)                                    PP0879 12-Dec-97 A Device and Method (IR18)                                    PP0883 12-Dec-97 A Device and Method (IR19)                                    PP0880 12-Dec-97 A Device and Method (IR20)                                    PP0881 12-Dec-97 A Device and Method (IR21)                                  ______________________________________                                    

DotCard Technologies

Further, the present application may include the utilization of a data distribution system such as that described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                       Provisional                                                                    Number Filing Date Title                                                     ______________________________________                                         PP2370   16-Mar-98  Data Processing Method and Apparatus                           (Dot01)                                                                      PP2371 16-Mar-98 Data Processing Method and Apparatus                            (Dot02)                                                                    ______________________________________                                    

Artcam Technologies

Further, the present application may include the utilization of camera and data processing techniques such as an Artcam type device as described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                       Provisional Filing                                                             Number Date Title                                                            ______________________________________                                         PO7991   15-Jul-97 Image Processing Method and Apparatus                           (ART01)                                                                      PO8505 11-Aug-97 Image Processing Method and Apparatus                           (ART01a)                                                                     PO7988 15-Jul-97 Image Processing Method and Apparatus                           (ART02)                                                                      PO7993 15-Jul-97 Image Processing Method and Apparatus                           (ART03)                                                                      PO8012 15-Jul-97 Image Processing Method and Apparatus                           (ART05)                                                                      PO8017 15-Jul-97 Image Processing Method and Apparatus                           (ART06)                                                                      PO8014 15-Jul-97 Media Device (ART07)                                          PO8025 15-Jul-97 Image Processing Method and Apparatus                           (ART08)                                                                      PO8032 15-Jul-97 Image Processing Method and Apparatus                           (ART09)                                                                      PO7999 15-Jul-97 Image Processing Method and Apparatus                           (ART10)                                                                      PO7998  5-Jul-97 Image Processing Method and Apparatus                           (ART11)                                                                      PO8031 15-Jul-97 Image Processing Method and Apparatus                           (ART12)                                                                      PO8030  5-Jul-97 Media Device (ART13)                                          PO8498 11-Aug-97 Image Processing Method and Apparatus                           (ART14)                                                                      PO7997 15-Jul-97 Media Device (ART15)                                          PO7979 15-Jul-97 Media Device (ART16)                                          PO8015 15-Jul-97 Media Device (ART17)                                          PO7978  5-Jul-97 Media Device (ART18)                                          PO7982 15-Jul-97 Data Processing Method and Apparatus                            (ART19)                                                                      PO7989  5-Jul-97 Data Processing Method and Apparatus                            (ART20)                                                                      PO8019 15-Jul-97 Media Processing Method and Apparatus                           (ART21)                                                                      PO7980 15-Jul-97 Image Processing Method and Apparatus                           (ART22)                                                                      PO7942  5-Jul-97 Image Processing Method and Apparatus                           (ART23)                                                                      PO8018 15-Jul-97 Image Processing Method and Apparatus                           (ART24)                                                                      PO7938 15-Jul-97 Image Processing Method and Apparatus                           (ART25)                                                                      PO8016 15-Jul-97 Image Processing Method and Apparatus                           (ART26)                                                                      PO8024 15-Jul-97 Image Processing Method and Apparatus                           (ART27)                                                                      PO7940  5-Jul-97 Data Processing Method and Apparatus                            (ART28)                                                                      PO7939 15-Jul-97 Data Processing Method and Apparatus                            (ART29)                                                                      PO8501 11-Aug-97 Image Processing Method and Apparatus                           (ART30)                                                                      PO8500  1-Aug-97 Image Processing Method and Apparatus                           (ART31)                                                                      PO7987 15-Jul-97 Data Processing Method and Apparatus                            (ART32)                                                                      PO8022 15-Jul-97 Image Processing Method and Apparatus                           (ART33)                                                                      PO8497 11-Aug-97 Image Processing Method and Apparatus                           (ART30)                                                                      PO8029 15-Jul-97 Sensor Creation Method and Apparatus                            (ART36)                                                                      PO7985 15-Jul-97 Data Processing Method and Apparatus                            (ART37)                                                                      PO8020 15-Jul-97 Data Processing Method and Apparatus                            (ART38)                                                                      PO8023 15-Jul-97 Data Processing Method and Apparatus                            (ART39)                                                                      PO9395 23-Sep-97 Data Processing Method and Apparatus                            (ART4)                                                                       PO8021 15-Jul-97 Data Processing Method and Apparatus                            (ART40)                                                                      PO8504  1-Aug-97 Image Processing Method and Apparatus                           (ART42)                                                                      PO8000 15-Jul-97 Data Processing Method and Apparatus                            (ART43)                                                                      PO7977 15-Jul-97 Data Processing Method and Apparatus                            (ART44)                                                                      PO7934 15-Jul-97 Data Processing Method and Apparatus                            (ART45)                                                                      PO7990 15-Jul-97 Data Processing Method and Apparatus                            (ART46)                                                                      PO8499 11-Aug-97 Image Processing Method and Apparatus                           (ART47)                                                                      PO8502 11-Aug-97 Image Processing Method and Apparatus                           (ART48)                                                                      PO7981 15-Jul-97 Data Processing Method and Apparatus                            (ART50)                                                                      PO7986 15-Jul-97 Data Processing Method and Apparatus                            (ART51)                                                                      PO7983 15-Jul-97 Data Processing Method and Apparatus                            (ART52)                                                                      PO8026 15-Jul-97 Image Processing Method and Apparatus                           (ART53)                                                                      PO8027 15-Jul-97 Image Processing Method and Apparatus                           (ART54)                                                                      PO8028 15-Jul-97 Image Processing Method and Apparatus                           (ART56)                                                                      PO9394 23-Sep-97 Image Processing Method and Apparatus                           (ART57)                                                                      PO9396 23-Sep-97 Data Processing Method and Apparatus                            (ART58)                                                                      PO9397 23-Sep-97 Data Processing Method and Apparatus                            (ART59)                                                                      PO9398 23-Sep-97 Data Processing Method and Apparatus                            (ART60)                                                                      PO9399 23-Sep-97 Data Processing Method and Apparatus                            (ART61)                                                                      PO9400 23-Sep-97 Data Processing Method and Apparatus                            (ART62)                                                                      PO9401 23-Sep-97 Data Processing Method and Apparatus                            (ART63)                                                                      PO9402 23-Sep-97 Data Processing Method and Apparatus                            (ART64)                                                                      PO9403 23-Sep-97 Data Processing Method and Apparatus                            (ART65)                                                                      PO9405 23-Sep-97 Data Processing Method and Apparatus                            (ART66)                                                                      PP0959  6-Dec-97 A Data Processing Method and Apparatus                          (ART68)                                                                      PP1397 19-Jan-98 A Media Device (ART69)                                      ______________________________________                                     

We claim:
 1. A thermal actuator in a micro-electro mechanical system, comprising a heater element formed from a first conductive material, said heater element being encased in a second non-conductive thermally expansive material, wherein said heater element is corrugated so as to increase the rate of thermal transfer to said second non-conductive thermally expansive material.
 2. A thermal actuator as claimed in claim 1 wherein said thermal actuator is utilized in the ejection of ink from an ink ejection nozzle. 